"use strict";
//加载所需要的模块
var http = require('http');
var url = require('url');
var fs = require('fs');
var path = require('path');
var cp = require('child_process');

//创建服务
var httpServer = http.createServer(processRequest);

var port = 8080;

//指定一个监听的接口
httpServer.listen(port, function() {
	console.log(`app is running at port:${port}`);
	cp.exec(`explorer http://localhost:${port}/views/login.html`, function() {});
});

//响应请求的函数
function processRequest(request, response) {
	//mime类型
	var mime = {
		"css": "text/css",
		"gif": "image/gif",
		"html": "text/html",
		"ico": "image/x-icon",
		"jpeg": "image/jpeg",
		"jpg": "image/jpeg",
		"js": "text/javascript",
		"json": "application/json",
		"pdf": "application/pdf",
		"png": "image/png",
		"svg": "image/svg+xml",
		"swf": "application/x-shockwave-flash",
		"tiff": "image/tiff",
		"txt": "text/plain",
		"wav": "audio/x-wav",
		"wma": "audio/x-ms-wma",
		"wmv": "video/x-ms-wmv",
		"xml": "text/xml"
	};

	//request里面切出标识符字符串
	var requestUrl = request.url;
	//url模块的parse方法 接受一个字符串，返回一个url对象,切出来路径
	var pathName = url.parse(requestUrl).pathname;

	//对路径解码，防止中文乱码
	var pathName = decodeURI(pathName);

	//解决301重定向问题，如果pathname没以/结尾，并且没有扩展名
	if (!pathName.endsWith('/') && path.extname(pathName) === '') {
		pathName += '/';
		var redirect = "http://" + request.headers.host + pathName;
		response.writeHead(301, {
			location: redirect
		});
		//response.end方法用来回应完成后关闭本次对话，也可以写入HTTP回应的具体内容。
		response.end();
	}

	//获取资源文件的绝对路径
	var filePath = path.resolve(__dirname + pathName);
	console.log(filePath);
	//获取对应文件的文档类型
	//我们通过path.extname来获取文件的后缀名。由于extname返回值包含”.”，所以通过slice方法来剔除掉”.”，
	//对于没有后缀名的文件，我们一律认为是unknown。
	var ext = path.extname(pathName);
	ext = ext ? ext.slice(1) : 'unknown';

	//未知的类型一律用"text/plain"类型
	var contentType = mime[ext] || "text/plain";

	fs.stat(filePath, (err, stats) => {
		if (err) {
			response.writeHead(404, {
				"content-type": "text/html"
			});
			response.end("<h1>404 Not Found</h1>");
		}
		//没出错 并且文件存在
		if (!err && stats.isFile()) {
			readFile(filePath, contentType);
		}
		//如果路径是目录
		if (!err && stats.isDirectory()) {
			var html = "<head><meta charset = 'utf-8'/></head><body><ul>";
			//读取该路径下文件
			fs.readdir(filePath, (err, files) => {
				if (err) {
					console.log("读取路径失败！");
				} else {
					//做成一个链接表，方便用户访问
					var flag = false;
					for (var file of files) {
						//如果在目录下找到index.html，直接读取这个文件
						if (file === "index.html") {
							readFile(filePath + (filePath[filePath.length - 1] == '/' ? '' : '/') + 'index.html', "text/html");
							flag = true;
							break;
						};
						html += `<li><a href='${file}'>${file}</a></li>`;
					}
					if (!flag) {
						html += '</ul></body>';
						response.writeHead(200, {
							"content-type": "text/html"
						});
						response.end(html);
					}
				}
			});
		}

		//读取文件的函数
		function readFile(filePath, contentType) {
			response.writeHead(200, {
				"content-type": contentType
			});
			//建立流对象，读文件
			var stream = fs.createReadStream(filePath);
			//错误处理
			stream.on('error', function() {
				response.writeHead(500, {
					"content-type": contentType
				});
				response.end("<h1>500 Server Error</h1>");
			});
			//读取文件
			stream.pipe(response);
		}
	});
}